What This Coin Looks Like (Obverse, Reverse, Mint Mark Location, Special Features, etc.): The 1979 Type 2 Clear S Washington Quarter has a much clearer and well-defined S mintmark and is also only found as a proof coin. Depicted below is an example comparison image between the type 1 filled "S" vs type 2 clear "S":
Coin Value Chart: Typical Coin Prices, Values and Worth in USD based on Grade/Condition